Meanwhile, a source previously claimed the Adore You singer played it "pretty cool" when he was robbed.
An insider said: "He actually played it pretty cool, quickly giving the assailant cash, keeping himself and the guy calm and getting the situation over with. Understandably though it left him very shaken up afterwards."
Metropolitan Police have confirmed the incident did take place, but did not mention the One Direction star.
They said in a statement: "Police are investigating reports of a knifepoint robbery in Hampstead. Officers were contacted on Saturday, 15 February regarding the incident which happened at 23.50hrs on Friday, 14 February. It was reported that a man in his 20s was approached by another man and threatened him with a knife. The victim was not injured however, cash was taken from him. No arrests and enquiries are ongoing."